NMR-based isotope editing, chemoselection and isotopomer distribution analysis in stable isotope resolved metabolomics

NMR is a very powerful tool for identifying and quantifying compounds within complex mixtures without the need for individual standards or chromatographic separation. Stable Isotope Resolved Metabolomics (or SIRM) is an approach to following the fate of individual atoms from precursors through metabolic transformation, producing an atom-resolved metabolic fate map. However, extracts of cells or tissue give rise to very complex NMR spectra. While multidimensional NMR experiments may partially overcome the spectral overlap problem, additional tools may be needed to determine site-specific isotopomer distributions. NMR is especially powerful by virtue of its isotope editing capabilities using NMR active nuclei such as 13C, 15N, 19F and 31P to select molecules containing just these atoms in a complex mixture, and provide direct information about which atoms are present in identified compounds and their relative abundances. The isotope-editing capability of NMR can also be employed to select for those compounds that have been selectively derivatized with an NMR-active stable isotope at particular functional groups, leading to considerable spectral simplification. Here we review isotope analysis by NMR, and methods of chemoselection both for spectral simplification, and for enhanced isotopomer analysis.

Classification of three prognostically different groups of head and neck cancer patients based on their metabolic response to induction chemotherapy (IC-1)

OBJECTIVES

There exist no uniform decision criteria for conservative organ preservation treatments in head and neck cancer patients. Even with ¹⁸F-FDG-PET/CT after induction chemotherapy patient selection is challenging. This study correlated metabolic tumor response with treatment types and recurrence patterns.

MATERIALS AND METHODS

Decrease in SUVmax in ¹⁸F-FDG-PET/CT was measured 21-28 days after IC-1 in 102 patients and correlated to cancer-specific endpoints.

RESULTS

Residual SUVmax (resSUVmax) values were uniformly distributed across five cut-off levels (0-0.2 vs. >0.2-0.4 vs. >0.4-0.6 vs. >0.6-0.8 vs. >0.8) containing 20%, 25% 25%, 15% and 15% of patients. Patients were stratified into three response categories according to residual SUVmax (Group A: 0-0.4 = high response Group B: >0.4-0.8 = moderate response, Group C > 0.8 = non-response), 5-year local control rates were 90.5% (Group A) vs. 78.9% (Group B; univariate p = 0.07, multivariate: HR: 3.6, p = 0.03) vs. 49.4% (Group C vs. B; univariate p = 0.04, multivariate: HR 5.5, p < 0.01). After IC-1, Group A received chemoradiotherapy (CRT) only. Group B received surgery plus either (chemo)radiotherapy (B_S + RT/CRT) or chemoradiotherapy (B_CRT), yielding local control rates of 100% and 74.2% (p = 0.11). Group C received surgery plus CRT or CRT alone; both achieved equally poor local control (p = 0.71). Group C had significantly worse distant metastasis-free survival and overall survival than Groups A and B (p < 0.05).

CONCLUSION

Metabolic response after IC-1 differentiates HNC patients into three subgroups predicting local tumor control. Non-response was associated with a poor outcome.

Organ Preservation Protocols in T4 Laryngeal Cancer: a Review of the Literature

Population-based studies indicate that chemoradiation has become the most popular treatment for advanced laryngeal cancers; however, by extrapolating trial results to the general population, several issues have emerged, such as reduced overall survival, non-functional laryngeal preservation, and poor response to treatment. Although included in these trials, T4 laryngeal and hypopharyngeal cancers with cartilage invasion formed a small percentage of these patients and questions over whether they were appropriately staged remain unanswered. Literature on the use of chemoradiation in this set of patients, including the challenges, treatment considerations, and factors predicting response to treatment and outcomes, was reviewed. Current evidence indicates that all patients of T4 laryngeal and hypopharyngeal cancer are not suitable candidates for organ preservation; this modality should be offered only to select patients with good performance status and access to rehabilitative care and regular follow-up in order to achieve good results.

Comparison between chemoselection and definitive radiotherapy in patients with cervical esophageal squamous cell carcinoma

BACKGROUD

Laryngeal preservation is an important consideration when treating cervical esophageal cancers (CECs) such as laryngeal cancer. The standard treatment for CEC allowing laryngeal preservation is chemoradiotherapy. However, in cases of laryngeal cancer, chemoselection has also been applied as a treatment strategy that promotes larynx preservation. This strategy involves assigning the appropriate radical treatment according to the primary tumor's response to induction chemotherapy. Since there have been no studies of the application of chemoselection in CEC cases, the present study compared the results, including laryngeal preservation rates, obtained upon applying chemoselection and chemoradiotherapy to CEC.

STUDY DESIGN

This was a retrospective cohort study of cervical esophageal squamous cell carcinoma patients treated using chemoselection or chemoradiotherapy at Aichi Cancer Center Hospital between January 2000 and March 2013. A total of 42 patients were enrolled.

RESULTS

The 2-year overall survival and laryngeal preservation rates for the chemoselection group versus the primary radiotherapy group were 65.1 and 57.3 versus 40 and 83.3%, respectively (P = 0.017 and P = 0.122, respectively). The 2-year locoregional control rates for the chemoselection and primary radiotherapy groups were 68 and 25%, respectively (P = 0.045).

CONCLUSION

The chemoselection group achieved favorable results. Therefore, chemoselection can be applied as a treatment strategy for CEC.